The problem with on-demand is that it takes time and energy to go actually demand it. With radio, if you are working in the garage or garden or on a jobsite, you just tune into some station, and you get guys talking about fixing cars or something and that's it. With youtube or spotify or whatever, you have to go search for something interesting, it lasts for 15 minutes, and then you have to search again. Or maybe you get a podcast that last an hour. But it's never set and forget like radio. It's all just a waste if time unless you have something very specific you want to hear, rather than just background chit chat.